This invention relates to retainer systems for wear parts including ground engaging tools and other wear parts and components of earthmoving and mining equipment. The invention has particular application to wear parts for excavator buckets and dragline buckets and the invention will be described with particular reference to such application. However, the invention also has application to wear parts for other types of equipment, for example, shovel buckets, bucket loaders, bulldozer blades, drotts, bobcats, and backhoes. The invention also has application to retainer systems for load bearing pins such as trunnion pins, anchor pins and the like, especially pins which are subject to significant wear and have to be replaced fairly often but it may also have application to other types of wear parts or pins which have to be reliably secured or locked in a working position. In this specification, the term “wear parts” generally includes nose mounts, teeth and adaptors, for mounting the teeth to the nose mounts, lips and lip shrouds, wing shrouds, drag hitch protectors, anchor brackets and pins, drag pins and socket brackets, trunnion brackets and pins and similar wear parts even though the invention will be described with particular reference to nose mounts, teeth and adaptors.
Typically, excavator buckets, dragline buckets and the like have a base or floor with a cutting edge or lip to which ground engaging tools are fitted to engage the ground or spoil which is to be excavated or loaded as the case may be and to protect the lip from wear. The ground engaging tools which are generally subject to the greatest wear are the teeth and a number of parts are associated with the teeth. The first component, often called the nose or nose mount, is usually fixed in a permanent or semi-permanent manner to the base of the bucket or the lip by welding and protrudes forward from the lip. The second component is releasably mounted on or to the nose so that it can be replaced when it reaches a predetermined wear condition. In some types of equipment the second component is the cutting tip, tooth, or tooth point which engages the ground at its front edge and suffers the main wear while in other equipment, the second component is an adaptor to which a third component being the cutting tip or tooth is releasably fitted which in turn suffers the main wear while the adaptor suffers lesser wear. Thus, it will be understood that while the teeth in a three component system will have a much shorter life than the adaptors, the adaptors themselves do eventually wear out and have to be replaced. Even the nose may wear out long before the bucket floor and walls and will have to be replaced but in the case of the noses, they can be cut away from the base and be replaced by new noses which can be welded to the base but that requires substantial downtime for a fairly substantial operation. In the case of a two component system, while the releasable teeth can be replaced relatively easily, if the nose wears out, a fairly substantial operation is required to replace them as with a three component system.
Typically, the nose includes a forwardly extending protuberance which is adapted to engage in a complementary cavity provided in the tooth, or the adaptor in a three component system. In a two component system, the adaptor has a cavity opening at one end in which the complementary protuberance on the nose engages and a protuberance at the other end which is adapted to engage in the complementary tooth cavity. The two components are commonly releasably secured together by one or more locking pins which lock the tooth and the underlying adaptor together or the adaptor and the underlying nose in the case of a three component system. There are various securing systems available which are commonly referred to as retaining systems.
In one known retainer system, a tapered pin is driven through aligned holes or passages extending through the tooth and the adaptor from top to bottom or the adaptor and the nose. However, the passage causes a weakness in the nose or the adaptor (in a three component system) which can lead to failure. In another case, two opposed relatively short locking pins located in the nose are arranged to be extended into complementary passages or openings in the opposed side walls of the tooth or adaptor which is mounted on the nose.
It will be appreciated that the cavities and protuberances are shaped to inhibit relative movement between the engaging components when in operation, although the presently known systems do not inhibit relative movement as well as desired. Further, the presently available retaining systems do not provide the reliability or efficiency of operation desired.
While teeth and adaptors are subject to more wear than other components and consequently will likely benefit from the present invention more than other wear parts, there are other wear parts which do require replacement throughout the life of a bucket, for example, wing shrouds, drag hitch protectors, anchor brackets and pins, drag pins and socket brackets, trunnion brackets and pins, and such components will also likely benefit from the present invention. Some such components may not be commonly referred to as wear parts in mining and earthmoving industries but in this specification, such components are considered to be “wear parts”.